Extra armor aims to eliminate fires due to battery punctures.

Tesla Motors founder Elon Musk has taken to Medium.com to post about a design change to the expensive-but-awesome Model S electric car: all Model S vehicles manufactured after March 6, 2014 will come with additional titanium and aluminum armor on their underbellies. The Model S carries its thousands of battery cells in a sealed enclosure below the floorpan, and the added armor is intended to protect the enclosure from puncture even under extreme conditions. This in turn should reduce the chances of Model S vehicles catching on fire.

Not that the cars catching on fire is much of a thing; Musk is quick to point out that there have been only two Tesla fires resulting from road accidents (one of which involved a Model S being driven at 110 miles per hour directly into—and then through—a concrete wall), versus hundreds of thousands of gasoline vehicle fires last year. Nonetheless, Musk has directed his company to improve the car's battery armor in an effort to assure customers (and investors) that the Model S really and truly isn't going to burst into flames if you drive over a curb.

The new armor takes the form of a three-part system: there's a big hollow aluminum bar to deflect objects, a large titanium plate to absorb impacts, and an angled aluminum extrusion to cause the car to "ramp up and over" objects that can't be crushed or flung aside.

To demonstrate the new armor's efficacy, Musk posted three animated GIFs of the new system destroying a block of concrete, brushing aside a three-ball steel trailer hitch, and pulverizing an alternator.

Model S 1, trailer hitch 0.

Model S 1, alternator 0.

According to Musk, the added protection will have a negligible effect on the car's range and handling. More importantly to customers, the additional armor will not raise the sticker price of the vehicle. Existing Model S owners can bring their cars in to have the armor installed at no cost, or they can have it automatically installed the next time they take their cars in for servicing.

Promoted Comments

On one hand, it's pretty cool to see a company react this quickly with this much of an upgrade. On the other hand, it's ridiculous that this is what he has to do to counteract the response to two fires.

Tesla is still growing quickly (for a good reason), but giving such a big upgrade "free of charge" is surely going to impact their bottom line. (The pun is accidental!) Titanium isn't cheap.

It isn't as outrageously expensive as some people would have you believe, either. Onlinemetals.com will sell you a 24"x24" sheet of 1/8" titanium for $660 and I'm sure Tesla can get it for a lot less than that; step down to 0.093" and the price drops to $414. If a couple hundred bucks adds to the "safest car ever made" reputation that they're accruing then it's probably money well spent.

[edit] It's possible that Tesla is using a better alloy than what I linked above, such as 6Al-4V. Maybe a metallurgist can chime in with a more accurate estimate, but my number disproves the "OMG titanium costs a fortune" thinking that seems to be pervasive.

4ftx8ft x 0.020" Grade 2 Titanium is going to run about 15lbs. Price is probably around $200 in commercial quantities (source - worked for largest producer in the world).

Lee Hutchinson / Lee is the Senior Reviews Editor at Ars and is responsible for the product news and reviews section. He also knows stuff about enterprise storage, security, and manned space flight. Lee is based in Houston, TX.